Grow Light Electricity Cost Calculator
Find out what your grow lights cost to run. Enter the wattage, how many hours a day they are on and your electricity price.
How the calculation works
Electricity is billed in kilowatt-hours (kWh). One kWh is 1,000 watts running for one hour:
kWh per day = watts × number of lights × hours per day ÷ 1,000 and cost = kWh × price per kWh
Example: one 200 W light on 16 hours a day uses 200 × 16 ÷ 1,000 = 3.2 kWh a day. At $0.15 per kWh that is $0.48 a day, 3.2 × 30 × 0.15 = $14.40 for a 30 day month and 3.2 × 365 × 0.15 = $175.20 a year.
The monthly figure uses 30 days and the yearly figure 365 days. The currency does not matter, so enter your price in dollars, pounds or euros and read the results in the same currency. To check whether your lights give your plants enough light, try the DLI calculator.
Estimates only. Real draw varies with dimming, heat and the age of the power supply, so a plug-in power meter is the most accurate way to measure.
Frequently asked questions
Which wattage should I use, the LED rating or the wall draw?
Use what the light actually draws from the wall. Many LED lights are sold by a comparison to older lamps, and the real draw is lower. The label, the power supply plate or a plug-in power meter will show it. If the light is dimmed, use the dimmed wattage.
Where do I find my electricity price?
On your bill, as a price per kWh (kilowatt-hour). If your bill shows tiered or time-of-use rates, use the rate that applies when the lights are on, or an average.
Does the cost include the pump and fans?
Not unless you add them. Enter the total wattage of everything that runs on the same schedule, or run the calculator again for each device and add the results.
How long should I run the lights?
It depends on the plant. Leafy crops and herbs are often given 14 to 18 hours a day. Follow the guidance for your crop, and use the DLI calculator to check the total light your plants get.